[Bug]: Slow `/apps/files/tags` Loading

[fa0311]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

When accessing https://example.com/apps/files/tags, the page takes 15 seconds to load. The Nextcloud instance experiencing this issue has 6,300 tags and 280,000 tag mappings.

Upon opening the developer console, the PROPFIND request to https://example.com/remote.php/dav/systemtags/ takes 10 seconds. It seems that this API is intended to retrieve all tag information at once.

A similar API, https://example.com/remote.php/dav/systemtags-assigned/image/, responds in 1 second. The reason for the 10x difference in performance is unclear.

It appears that the issue could be resolved by implementing pagination, such as offset or cursor-based loading, to load 100 items at a time, rather than loading everything in one go.

Steps to reproduce

1. Open https://example.com/apps/files/tags

Expected behavior

...

Nextcloud Server version

30

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.1

Web server

Nginx

Database engine version

MariaDB

Is this bug present after an update or on a fresh install?

None

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

...

List of activated Apps

...

Nextcloud Signing status

...

Nextcloud Logs

...

Additional info

No response

[skjnldsv]

The Nextcloud instance experiencing this issue has 6,300 tags and 280,000 tag mappings.

Can you describe your use case for having that many tags and nodes?

[fa0311]

Can you describe your use case for having that many tags and nodes?

My Nextcloud contains 40,000 photos and 30,000 screenshots taken by me and my family. These are categorized by multiple AI systems.

• https://github.com/nextcloud/recognize
• https://github.com/fa0311/DeepNextcloud

[joshtrichards]

Do you have any warnings under Admin settings->Overview about missing indexes/etc?

[fa0311]

Do you have any warnings under Admin settings->Overview about missing indexes/etc?

I always make an effort to address any setup warnings that appear under Admin settings -> Overview.

Currently, on my server (Nextcloud v31.0), I confirmed that this issue has been resolved — the /apps/files/tags API is now responding within 1.5 seconds.

I'm not sure whether this was fixed by a version upgrade or by resolving one of the newer setup warnings (such as the ROW_FORMAT warning mentioned in #48547), but the problem no longer occurs on my instance.